R. Saikia and L.R. Saikia
Abstract
Phosphate Solubilizing Bacteria (PSB) solubilizes insoluble phosphates. Two strains of PSB, 2b3 and 2b5 were isolated from Lablab purpureus (L.) Sweet rhizosphere soil based on the formation of halozone in Pikovskaya agar plates. Phosphate solubilization in Pikovskaya broth containing either aluminium, ferric or tricalcium phosphates in different pH conditions was estimated. Both the strains were subjected to salinity stress. Morphology and biochemical characters of the bacterial isolates were studied and identified by 16s rRNA gene sequencing. The two bacterial strains 2b3 and 2b5 were identified as Burkholderia sp. and Burkholderia cepacia respectively. The Phosphate Solubilization Index of Burkholderia sp. and Burkholderia cepacia were 2.43±0.057 and 2.36 ± 0.200 respectively. Both the strains showed higher phosphate solubilization in broth containing tricalcium phosphates in comparison to aluminium and ferric phosphates. Burkholderia cepacia (2b5) showed higher phosphate solubilization than 2b3 (Burkholderia sp.) after 144 hours in all the three media. Phosphate solubilized in broth containing aluminium phosphate, ferric phosphate and tricalcium phosphate by 2b5 after 144 hours were 117.53±9.13, 109.15±5.43 and 260.17±11.81 respectively. Both the isolates showed ammonia production and Burkholderia cepacia (2b5) showed better growth in agar plates with NaCl than Burkholderia sp. (2b3). The results indicate that the isolated bacterial strains are potent mineral phosphate solubilizers and further studies will help in the use of these two strains as biofertilizers.